Increased CPA6 promoter methylation in focal epilepsy and in febrile seizures

1. INCREASED CPA6 PROMOTER
METHYLATION IN FOCAL
EPILEPSY AND IN
FEBRILE SEIZURES
Annick Salzmann, PhD
Service de Médecine Génétique (HUG)
Département de Psychiatrie (UNIGE)
7ème Journée de la Recherche Clinique
8 mai 2014

2. • Epilepsy
• Focal Epilepsy & Febrile Seizures
• Carboxypeptidase A6 (CPA6)
• Epigenetics of epilepsy
• CPA6 DNA Methylation & Epilepsy
• Perspectives

3. EPILEPSY
• Chronic neurological disorder à affects all ages
• Defined by 2 or more unprovoked seizures
• 50 million people worldwide (WHO 2009)
• 0.5–1% world population
• Epileptic phenomenen
‣ Hyperexcitability & Hypersynchrony

4. FOCAL EPILEPSY
• Most common form of epilepsy (60%)
• Localisation-related – Temporal lobe epilepsy
• Resistance to anti-epileptic drugs
• Surgical resection of anterior temporal lobe structures
• Antecedent of febrile seizures
• Complex disorder = genetic + environment

5. FEBRILE SEIZURES
• Not considered to be an epileptic condition
• Provoked by fever (>38.5°)
• Prevalence: 2–5%
• Onset age: 3 months and 5 years
• Epilepsy occurs 2–10 times more
• Important genetic predisposition

7. CONSANGUINEOUS FAMILY
7
Complex Febrile Seizures + Temporal Lobe Epilepsy
Complex Febrile Seizures
One Simple Febrile Seizure
Several Simple Febrile Seizures
1 2
5
3 4 5 6
4
II
III
1 2 3 6 7 8 9 10
I
M/– M/–
M/– M/–
Founder mutation = M
M/M M/M M/M M/MM/–
or
–/–
M/–
or
–/–
M/–
or
–/–
M/–
or
M/M
Common
Ancestor
Autosomal Recessive Model

8. CARBOXYPEPTIDASE A6
(CPA6) MUTATION
CPA6 Protein
Salzmann et al. Hum Mutat, 2012

9. CARBOXYPEPTIDASE A6 (CPA6)
• Member of the M14 metallocarboxypeptidase family
• Highly expressed in human embryonic brain and in fetal
umbilical cord blood (Wei et al., J. Biol. Chem. 2002)
• 50-kDa pro-CPA6 → 37-kDa active form secreted into the
extracellular matrix (Lyons et al., J. Biol. Chem. 2008)
• Cleaves C-terminal hydrophobic residues → role in
neuropeptides regulation (Lyons et al., J. Biol. Chem. 2008)

11. CPA6 MUTATIONS IN
EPILEPTIC PATIENTS
CPA6 Protein
7 missense variants
Consanguineous
FEB11/ELT5 family
c.809C>T → TT
3 FE patients
c.799G>A → GA1 TLE patient
c.843A>G → AG
1 TLE patient
c.875C>G → CG
Association
Study
Association
Study
Association
Study
Sapio et al. J Biological Chemistry, 2012

12. • Epilepsy
• Focal Epilepsy & Febrile Seizures
• Carboxypeptidase A6 (CPA6)
• Epigenetics of epilepsy
• CPA6 DNA Methylation & Epilepsy
• Perspectives

13. EPIGENETICS
• Regulation of biological processes from conception to death
of an organism
• Mitotically and/or meiotically heritable variations in gene
functions, which are not due to changes in DNA sequence
• Essential for normal development, maintenance of cellular
homeostasis and functions of an adult organism

14. LIFE EPIGENETIC PROFIL
Foley et al.Am. J. Epidemiol. 2009

15. DNA METHYLATION
C
CH3
G
C
GCH3

16. METHYLATION HYPOTHESIS
IN EPILEPTOGENESIS
Kobow & Blümcke, Epilepsia, 2012

17. • Epilepsy
• Focal Epilepsy & Febrile Seizures
• Carboxypeptidase A6 (CPA6)
• Epigenetics of epilepsy
• CPA6 DNA Methylation & Epilepsy
• Perspectives

18. CPA6 CpGs IN PROMOTER

19. EPILEPTIC PATIENTS &
CONTROLS

20. INCREASED LEVEL OF
CPA6 METHYLATION
0
1
2
3
4
5
6
7
8
Controls FE FS
Treated
Controls
with AEDs
Healthy
Children
with FHE
Young
Controls
* ; # ; § ; $
** ; ## ; § § ; $ $
%Methylation

22. • Epilepsy
• Focal Epilepsy & Febrile Seizures
• Carboxypeptidase A6 (CPA6)
• Epigenetics of epilepsy
• CPA6 DNA Methylation & Epilepsy
• Perspectives

23. PERSPECTIVES
• In epilepsy field à Beginning of epigenetics research à A
few published studies and most related to DNA methylation
• New cohorts of patients
à Blood (DNA) collected after a first seizure
à Blood (DNA) collected after X seizures
à Comparison of DNA methylation level (EpiGenome wide)

24. Thank you for your attention